The present invention relates to a cellulose-containing composite. More particularly, the present invention relates to a cellulose-containing composite which comprises a particular fine cellulose and a low-viscosity water-soluble dietary fiber and which is superior in feeling when taken into the mouth, and which is also superior in shape retainability, and fluidity when made into a liquid food, etc. and further in effects as dietary fiber or as oil and fat substitute.
Cellulose has been used in foods for various purposes of, for example, imparting suspension stability, emulsion stability, shape retainability or cloudiness, or for adding dietary fiber. However, when cellulose is used alone as a stabilizer or the like, there have been cases that the addition effect is insufficient or the cellulose-added food gives slightly rough feeling to the tongue. Natural dietary fibers are ordinarily a composite of a water-insoluble dietary fiber and a water-soluble dietary fiber and these two kinds of dietary fibers differ in action in the intestinal tract. Therefore, the dietary fiber material used in food is preferred to be a combination of the above two kinds of dietary fibers. However, neither dietary fiber material nor combined dietary fiber material is currently available which has a low viscosity suitable for use in food, which has good feeling when taken into the mouth, and which has high stability.
In JP-B-57-14771 is described a composite comprising a microcrystalline cellulose, a dispersing agent (a gum) and a disintegrating agent in particular proportions. The composite has a high viscosity depending upon the kind of gum used and, therefore, it has given paste-like viscous feeling when taken into the mouth, in some cases. For example, Avicel RC-591 (trade name) (a product of Asahi Chemical Industry Co., Ltd.), which is a commercially marketed crystalline cellulose preparation, comprises a microcrystalline cellulose and, as a dispersing agent, sodium carboxymethylcellulose and, when dispersed in water in a 3% concentration, gives a high viscosity of 1,200 mPaxc2x7.
In JP-B-6-75474 is described a composition comprising a microcrystalline cellulose and galactomannan gum. The galactomannan gum used in this composition is an ordinary gum not subjected to any decomposition treatment and acts as a binder for the microcrystalline cellulose. Therefore, when the composition is stirred in water, the composition only swells, causes no disintegration into particles, and maintains the original state. Therefore, the composition has low suspension stability in water although it gives in-mouth feeling similar to that of fat and is suitable as a fat substitute for use in food.
In JP-A-6-135838 is described an oral or tube fed nutritious composition comprising a microcrystalline cellulose (as a water-insoluble dietary fiber) and an enzymatically hydrolyzed guar gum (as a water-soluble dietary fiber). In this composition, the microcrystalline cellulose and the enzymatically hydrolyzed guar gum are not in a composite form but in a simple mixture; therefore, the rough feeling of the microcrystalline cellulose is not sufficiently suppressed and the in-tube flowing-down property has not been sufficient.
In JP-A-7-173332 and JP-A-7-268129 are described composites comprising a fine cellulose and a hydrophilic substance and/or a water-soluble gum, which contain particles having particle diameters of 10 xcexcm or more, in an amount of 40% or less and which have a colloidal content (which is a yardstick for the amount of fine particles) of 65% or more. In the literature, polydextrose is shown as an example of the hydrophilic substance, and xanthan gum is shown as an example of the water-soluble gum. These composites, however, have a high colloidal content and accordingly high viscosity; therefore, when used in a food such as a drink or the like in an amount of 1% or more, they give viscous feeling and, when used in a tube fed liquid diet, it has been difficult to allow them to flow down at a sufficient speed.
In the above-mentioned JP-A-7-173332 and JP-A-7-268129 are shown dextrin as an example of the hydrophilic substance. Dextrin is a group of intermediates formed when starch is subjected to partial hydrolysis by the action of acid, enzyme, heat or the like, and it is often referred to in industry, as pyrodextrin obtained by dry method (Sogo Shokuhin Jiten (6th edition), pp. 617-618 (1989), edited by Yoshito Sakurai and published from Dobun Shoin). In the above literature, hydrolyzed starch is also mentioned; therefore, the dextrin mentioned in the literature refers to pyrodextrin. Incidentally, as is well known in the art, pyrodextrin includes white or yellow dextrin obtained by subjecting starch to pyrolysis using an acid catalyst, and British gum obtained by subjecting starch to pyrolysis using no acid, and each dextrin contains an indigestible component. However, the content of the indigestible component is at most about 40%, and more than half is digestible (K. Ohkuma et al., Denpun Kagaku, 37 (2), pp. 107-114 (1990)). That is, substances generally known as dextrin have been digestible. In contrast, the dextrin usable in the present invention which is indigestible as mentioned later, is different from the dextrin mentioned in the above literature, and has a meaning as a dietary fiber material in the present invention because it is indigestible.
In JP-A-7-70365 is described a composite of a fine cellulose and a polydextrose, which contains particles having particle diameters of 10 xcexcm or more, in an amount of 40% or less and which has a colloidal content of 50% or more. This composite has a low viscosity but contains no stabilizer such as gellan gum or the like; therefore, it has no long-term suspension stability. Moreover, in the composite, the cellulose particles are fine and tend to interact with milk protein, etc., and the polydextrose has no sufficient effect for reducing of the interaction; therefore, the system using the composite has tended to cause flocculation. In the literature is also described the use of dextrin. This dextrin, however, is different from the indigestible dextrin used in the present invention, for the same reason as mentioned above.
In WO 98/33394 is described a texture agent for food, obtained by mixing a microcrystalline cellulose and a polydextrose in water and drying the resulting mixture. The polydextrose is used only in the claims of the literature, and only maltodextrin is used in the Examples, etc. Therefore, the effect of the composition using a polydextrose is unclear from the above literature alone. However, the composition using a polydextrose is presumed to have insufficient stability at a low concentration, because the composition is thought to have the same effect as the composition using maltodextrin and because it is shown in the literature that the composition using maltodextrin gives a low viscosity at a low concentration but gives rise to precipitation of cellulose and resultant separation into two layers. The literature also has a description regarding a composition using xanthan gum in combination. Since the amount of xanthan gum used is 3% or more, the composition has a high viscosity of 525 mPaxc2x7s or more when made into a 2% suspension. In WO 98/33394 is disclosed neither data nor technical idea of cellulose-containing composite of low viscosity and high stability.
The present invention is intended to provide a cellulose-containing composite which has a low viscosity and excellent suspension stability when dispersed in water, which is good in feeling when taken into the mouth, superior suspension stability, shape retainability, and fluidity when made into a tube fed liquid diet, etc., and which has an effect of water-insoluble dietary fiber and an effect of water-soluble dietary fiber; and a food composition containing the composite.
The present inventors found out that a composite comprising a particular fine cellulose and a low-viscosity water-soluble dietary fiber has a low viscosity when dispersed in water and, since the fine cellulose has a small average particle size, gives no viscous feeling when used in foods and contributes to food stability such as shape retainability or the like. The present invention has been completed based on these findings.
The present invention lies in the following embodiments.
(1) A cellulose-containing composite comprising 20-99% by weight of a fine cellulose and 1-80% by weight of at least one low-viscosity water-soluble dietary fiber selected from the group consisting of 1) a hydrolyzed galactomannan, 2) an indigestible dextrin and 2) a mixture of a polydextrose and xanthan gum and/or gellan gum (the total amount of gellan gum and xanthan gum is 0.1% by weight or more but less than 3% by weight of the composite), in which composite the average particle size of the fine cellulose is 30 xcexcm or less when the composite is dispersed in water.
(2) A composite according to the above (1), which has a viscosity of 300 mPaxc2x7s or less when made into a suspension of 3% by weight of the composite.
(3) A composite according to the above (1), which has a colloidal content of less than 65% when the low-viscosity water-soluble dietary fiber is a mixture of a polydextrose and xanthan gum and/or gellan gum.
(4) A composite according to the above (1), which has a colloidal content of less than 65%.
(5) A composite according to the above (1), wherein the water-soluble dietary fiber is a mixture of a polydextrose and xanthan gum and/or gellan gum (the total amount of gellan gum and xanthan gum is 0.1% by weight or more but less than 3% by weight of the composite) and which composite has a colloidal content of less than 65%.
(6) A process for producing a cellulose-containing composite, which comprises mixing, in a wet state, 20-99% by weight of a fine cellulose and 1-80% by weight of at least one low-viscosity water-soluble dietary fiber selected from the group consisting of 1) a hydrolyzed gallactomannan, 2) an indigestible dextrin and 3) a mixture of a polydextrose and xanthan gum and/or gellan gum (the total amount of gellan gum and xanthan gum is 0.1% by weight or more but less than 3% by weight of the composite) and then drying the resulting mixture. This process is suitable as a process for producing any of the cellulose-containing composites of the above (1) to (5).
(7) A process for producing a cellulose-containing composite, which comprises simultaneously mixing and attriting, in a wet state, 20-99% by weight of a depolymerized cellulose and 1-80% by weight of at least one low-viscosity water-soluble dietary fiber selected from the group consisting of 1) a hydrolyzed gallactomannan, 2) an indigestible dextrin and 3) a mixture of a polydextrose and xanthan gum and/or gellan gum (the total amount of gellan gum and xanthan gum is 0.1% by weight or more but less than 3% by weight of the composite) and then drying the resulting mixture. This process is suitable as a process for producing any of the cellulose-containing composites of the above (1) to (5).
(8) A food containing a cellulose-containing composite set forth in any of the above (1) to (5).
(9) A food containing a cellulose-containing composite set forth in any of the above (1) to (5), wherein the composite is disintegrated and dispersed in the form of individual fine cellulose particles.
(10) A food according to the above (9), which is a tube fed liquid diet.
The cellulose-containing composite of the present invention is not only a mixture of the powder of fine cellulose with the powder of a low-viscosity water-soluble dietary fiber or the like but also the particles which contain, within one particle, one or more fine cellulose particles and the low-viscosity water-soluble dietary fiber, and optionally other components, wherein the low-viscosity water-soluble dietary fiber is present around any one of the fine cellulose particles or dried powder composed of a group of such particles.
The cellulose-containing composite of the present invention, when placed in water and stirred, is not dispersed in water in the form of the composite, but is disintegrated and dispersed in the form of individual fine cellulose particles.
When the present cellulose-containing composite is placed in water in a 1% concentration and dispersed by stirring, the fine cellulose of the composite has an average particle size of 30 xcexcm or less. In this case, the proportion of fine cellulose particles having particle sizes of 10 xcexcm or more is preferably 80% or less, in the particle size distribution. More preferably, the average particle size is 20 xcexcm or less and the proportion of particles having particle sizes of 10 xcexcm or more is 70% or less. Even more preferably, the average particle size is 3-10 xcexcm and the proportion of particles having particle sizes of 10 xcexcm or more is 50% or less. When the average particle size is more than 30 xcexcm, the composite gives rough feeling to the tongue when taken into the mouth in the form of a drink or a food, and further is low in properties such as stability and the like. As the average particle size of fine cellulose is made smaller, there tends to be less rough feeling to the tongue. However, when the average particle size is less than 3 xcexcm, the amount of colloidal content and thus the viscosity increases in some cases, which case is not desirable.
The cellulose-containing composite of the present invention has a low viscosity. It means that the composite has a low viscosity, preferably 300 mPaxc2x7or less as measured for a 3% aqueous dispersion. When the viscosity is more than 300 mPaxc2x7, the composite tends to have viscous feeling when taken into the mouth. When the composite is made into, in particular, a tube fed liquid diet, it is difficult to allow the liquid diet to flow at a certain or high speed, specifically at a speed of 200 g/hr or higher when a liquid diet containing about 1.5% of the composite is allowed to flow down through a tube having an inner diameter of 1 mm or less. Further, the tube fed liquid diet tends to clog the tube at the clamp portion when the flow speed is adjusted to a certain value, for example 170 g/hr, by throttling the clamp. The viscosity is preferably 100 mPaxc2x7or less, more preferably 50 mPaxc2x7or less.
The fine cellulose in the present invention is cellulose particles wherein the average particle size is 30 xcexcm or less. In this case, the proportion of fine cellulose particles having particle sizes of 10 xcexcm or more is 80% or less in the particle size distribution. Preferably, the average particle size is 20 xcexcm or less and the proportion of fine cellulose particles having particle sizes of 10 xcexcm or more is 70% or less. More preferably, the average particle size is 3-10 xcexcm and the proportion of fine cellulose particles having particle sizes of 10 xcexcm or more is 50% or less.
The hydrolyzed galactomannan is obtained by using, as the raw material, guar gum, locust bean gum or the like, all of which can be collected from bean seeds and are a galactomannan, and subjecting it to partial decomposition of galactomannan main molecular chain with an enzyme or the like. Since the galactomannan main molecular chain is decomposed, the hydrolyzed galactomannan is characterized in that its aqueous solution has a low viscosity as compared with the galactomannan before decomposition. The hydrolyzed galactomannan gives a viscosity of 300 mPaxc2x7or less, preferably 100 mpas or less, particularly preferably 10 mPaxc2x7s or less when dissolved in water in a 10% concentration. Incidentally, guar gum not subjected to any enzymatic hydrolysis gives a high viscosity of about 3,000 to 4,000 mPaxc2x7at a 1% concentration. Preferred as the hydrolyzed galactomannan is a guar gum enzymatic hydrolysis product for the availability. Its commercial products include xe2x80x9cSunfiberxe2x80x9d (trade name) (a product of Taiyo Kagaku Co., Ltd.), xe2x80x9cFiberon Sxe2x80x9d (trade name) (a product of Dainippon Pharmaceutical Co., Ltd.), etc.
The indigestible dextrin is obtained, for example, by heating a starch in the presence of an acid to obtain a pyrodextrin and then subjecting the pyrodextrin to enzymatic hydrolysis or further to fractionation with an ion exchange resin. The indigestible dextrin is an indigestible substance of highly branched structure wherein the dietary fiber has an average molecular weight of about 500 to 3,000, the glucose residue is bonded by an xcex1-1,4-, xcex1-1,6-, xcex2-1,2-, xcex2-1,3- or xcex2-1,6-glucoside bond, and part of the reducing terminal is levoglucosan (1,6-anhydroglucose). Commercial products of the sparingly digestible dextrin include xe2x80x9cPine Fiberxe2x80x9d (trade name), xe2x80x9cFibersol 2xe2x80x9d (trade name) (both are products of Matsutani Chemical Industry Co., Ltd.), etc. These products are characterized in that they give a low viscosity when dissolved in water and, unlike ordinary starches, are indigestible. In the present invention is used an indigestible dextrin which gives an aqueous solution of low viscosity similar to that given by the hydrolyzed galactomannan. As starches generally giving a low viscosity aqueous solution, there are hydrolyzed starch (HCS: hydrolyzed cereal solid), dextrin and maltodextrin; however, these are different from the indigestible dextrin used in the present invention because they are digestible. In the present invention is used an indigestible dextrin containing a dietary fiber component, i.e. an indigestible component in an amount of 50% or more, preferably 70% or more.
Polydextrose is a glucose polymer in which glucose molecules are randomly bonded to one another and which is highly branched. The polydextrose is hardly digested by human digestive enzymes and therefore functions as a dietary fiber. Polydextrose has a relatively low molecular weight, is well soluble in water and gives an aqueous solution of low viscosity; therefore, the polydextrose is in wide use as a water-soluble dietary fiber. Polydextrose can be produced, for example, by mixing glucose with a small amount of sorbitol, adding a small amount of citric acid, and heating the resulting mixture under reduced pressure. As usable commercial products, there are xe2x80x9cLitessexe2x80x9d, xe2x80x9cLitesse IIxe2x80x9d, xe2x80x9cLitesse IIIxe2x80x9d (all are trade names and products of Cultor Food Science Co., Ltd.), etc.
Polydextrose gives about the same low viscosity as the hydrolyzed galactomannan or the indigestible dextrin; however, being inferior in stability per se, it must be used in admixture with xanthan gum and/or gellan gum.
Xanthan gum has such a structure that the main chain has a molecular structure similar to that of cellulose wherein glucose residues are bonded in a straight chain by xcex2-1,4-glucoside bond, and that trisaccharides formed by bonding of xcex1-D-mannose, xcex2-D-glucuronic acid and xcex2-D-mannose are bonded, as side chains, to every other one of the glucose residues of the main chain. To the trisaccharide are bonded acetyl groups and pyruvic acid groups. Xanthan gum has a molecular weight of about 1,000,000 or more.
Gellan gum is a straight chain polymer containing, as constituent units, four kinds of saccharide molecules, i.e. xcex2-D-glucose having 1,3-bond, xcex2-D-glucuronic acid having 1,4-bond, xcex2-D-glucose having 1,4-bond and xcex1-L-rhamnose having 1,4-bond, wherein one glyceryl group and 1/2 (on an average) acetyl group are bonded to the glucose residue having 1,3-bond. This gellan gum is called native type gellan gum. It has a molecular weight of about 600,000 to 700,000. As usable commercial products, there are xe2x80x9cKelcogel LT-100xe2x80x9d (trade name) (a product of San-Ei Gen F.F.I., Inc.), etc.
Both xanthan gum and gellan gum are characterized in that they are soluble in water and give an aqueous solution of high viscosity. Xanthan gum and gellan gum may be mixed with polydextrose singly or in admixture. In the mixture with polydextrose, Xanthan gum and/or gellan gum is used in an amount of preferably 10% by weight or less. In the present invention, there is used, as such a mixture, one giving, when made into a 1% aqueous solution of Xanthan gum and/or gellan gum, a viscosity of 350 mPaxc2x7s or less, preferably 100 mPaxc2x7s or less, particularly preferably 10 mPaxc2x7s or less. The total amount of gellan gum and xanthan gum used must be 0.1 to 3% by weight of the present composite. When the total amount is less than 0.1% by weight, the resulting composite does not have satisfactory stability. When the total amount is more than 3% by weight, increased stability is obtained but low viscosity is impaired.
The cellulose-containing composite of the present invention comprises 20-99% by weight of a fine cellulose and 1-80% by weight of at least one low-viscosity water-soluble dietary fiber selected from the group consisting of 1) a hydrolyzed galactomannan, 2) an indigestible dextrin, and 3) a mixture of a polydextrose and xanthan gum and/or gellan gum (the total amount of gellan gum and xanthan gum is 0.1% by weight or more but less than 3% by weight of the composite). When the amount of the fine cellulose is less than 20% by weight, the composite shows no sufficient effect as a stabilizer when used, for example, for imparting shape retainability in baking a cake. When the amount of the fine cellulose is more than 99% by weight, the composite gives rough feeling to the tongue or dry (not moist) feeling in the mouth. When the amount of the low-viscosity water-soluble dietary fiber is less than 1% by weight, the fine cellulose of the composite is not dispersed into individual particles when the composite is placed in water and stirred. When the amount of the low-viscosity water-soluble dietary fiber is more than 80% by weight, the composite shows no sufficient effect as a stabilizer and moreover gives viscous feeling to the tongue.
The cellulose-containing composite of the present invention comprises preferably 40-90% by weight of a fine cellulose and 10-60% by weight of a low-viscosity water-soluble dietary fiber, particularly preferably 50-85% by weight of a fine cellulose and 15-50% by weight of a low-viscosity water-soluble dietary fiber.
In the cellulose-containing composite of the present invention, it is possible to as necessary use, besides the fine cellulose and the low-viscosity water-soluble dietary fiber, various components usable in foods, such as monosaccharide, oligosaccharide, sugar alcohol, starch, soluble starch, hydrolyzed starch, oil and fat, protein, table salt, other salt (e.g. phosphate), emulsifier, thickener and stabilizer, acidulant, spice, food color and the like. In order to control, in particular, the dispersing state of the composite, it is effective to use a thickener and stabilizer used in foods (e.g. xanthan gum, carrageenan, sodium carboxymethylcellulose, pectin or gellan gum), a saccharide and a starch (e.g. soluble starch or hydrolyzed starch), a dietary fiber (e.g. hydrolyzed pectin) singly or in combination. These components may be added during or after production of the present composite. The amounts of these components used should be appropriately determined in view of the required balance of functions (e.g. stability) and viscosity; however, when a hydrolyzed galactomannan or an indigestible dextrin is used as the low-viscosity water-soluble dietary fiber, use of 3% or less of xanthan gum or 1% or less of gellan gum can give a favorable result. A particularly preferred amount of the above components is 0.1 to 2.5% by weight based on the composite.
The cellulose-containing composite of the present invention is preferred to have a low colloidal content. In the present invention, xe2x80x9ccolloidal contentxe2x80x9d is a physical property value that is obtained unambiguously by the method disclosed on page 26, line 25 through page 27, line 27, infra, for the fine cellulose composite according to the present invention. Since a high colloidal content gives a high viscosity, the colloidal content is preferably 85% or less, more preferably less than 65%, particularly preferably 5 to 50%.
Also, when the present composite comprises 20-99% by weight of a fine cellulose and 1-80% by weight of a mixture of a polydextrose and xanthan gum and/or gellan gum (the total amount of gellan gum and xanthan gum is 0.1% by weight or more but less than 3% by weight of the composite), the colloidal content is preferred to be less than 65%. A colloidal content of 65% or higher results in a high viscosity and an increased reactivity with milk protein particles in an acidic environment (this invites reduced stability). Therefore, the colloidal content is preferably 5 to 50%, particularly preferably 10 to 40%.
The present composite comprising a fine cellulose and a low-viscosity water-soluble dietary fiber is not a mere mixture of a powdery fine cellulose and a powdery low-viscosity water-soluble dietary fiber, but is a composite obtained by mixing a fine cellulose and a low-viscosity water-soluble dietary fiber in a wet state, that is, in a slurry, paste, gel or cake state and then drying the resulting mixture. It is important that by conducting the mixing in a wet state, the surfaces of the fine cellulose particles are made well compatible with the low-viscosity water-soluble dietary fiber. It is speculated that after the drying step, an interaction occurs between the fine cellulose particles and the low-viscosity water-soluble dietary fiber and hence, in case these fine cellulose particles are dispersed into individual particles by stirring in water, a part of the low-viscosity water-soluble dietary fiber is remained attached to the surface of the fine cellulose particles. As a result, the aqueous dispersion of the composite has a decreased viscosity and shows reduced clogging at the portion of a clamp when flowing down in a tube, than a simple mixture of the above components. The water content in the mixture before drying is preferably about 30% by weight or more of the total weight of the mixture. A low water content is not preferred because a longer time is required for sufficient mixing of the fine cellulose and the low-viscosity water-soluble dietary fiber. The water content is more preferably about 50% or more.
The process for producing the cellulose-containing composite of the present invention is described specifically.
The cellulose-containing composite of the present invention can be obtained, for example, by subjecting a cellulose material (e.g. wood pulp, refined linters, regenerated cellulose or cereal- or fruit-derived vegetable fiber) to a depolymerization treatment (e.g. acid hydrolysis, alkali oxidative decomposition, enzymatic hydrolysis, steam explosion decomposition, hydrolysis by subcritical or supercritical water or a combination thereof) to obtain a cellulose having an average degree of polymerization of 30 to 375, then attriting the cellulose by applying a mechanical shear (a shear force) to make it into fine cellulose, adding thereto a low-viscosity water-soluble dietary fiber and mixing them, and drying the resulting mixture. It is particularly preferred to add a low-viscosity water-soluble dietary fiber to the depolymerized cellulose material, then conducting attrition and mixing simultaneously by applying a mechanical shear (this is wet co-attrition), and drying the resulting material to make a fine cellulose-containing composite. The present cellulose-containing composite may also be obtained by subjecting a cellulose material (e.g. wood pulp or bacterial cellulose) to a weak chemical treatment (not an ordinary chemical treatment), then conducting wet attrition or pulverizing by applying a mechanical shear to obtain a fine fibrous cellulose or a powdery cellulose, adding thereto a low-viscosity water-soluble dietary fiber, mixing and/or attriting them in the presence of water, and drying the resulting material to make a fine cellulose-containing composite.
The attritor used for wet attrition is appropriately selected depending upon the amount of water present in the attrition system and the intended degree of cellulose fineness achieved by attrition.
For example, when a sufficient mechanical shear is applied so as to obtain a fine cellulose having an average particle size of 8 xcexcm or less, a media agitating mill can be used (e.g. wet vibration mill, wet planetary vibration mill, wet ball mill, wet roll mill, wet coball mill or wet beads mill), a wet paint shaker, a high-pressure homogenizer, or the like. Effective as the high-pressure homogenizer is a type wherein a slurry is introduced into a small diameter orifice at a pressure of about 500 kgf/cm2 or more and face-to-face collision is allowed to take place at a high flow speed. When the above mill is used, the optimum solid concentration in slurry differs depending upon the kind of mill, but is appropriately about 3 to 25% by weight.
When a mechanical shear is applied so as to obtain a fine cellulose having an average particle size of 5 to 30 xcexcm, and when a slurry having a solid content of about 3 to 30% by weight is attrited, an attritor or a mixer can be used such as colloid mill, continuous ball mill, homogenizer, homomixer, propeller mixer or the like. When a cake having a higher solid content of about 20 to 50% by weight is attrited, there can be used a kneader, an automated mortar, an extruder or the like. A microfibrillated cellulose can be obtained by passing a suspension of a cellulose material through a high-pressure homogenizer several times at a pressure of 50 kgf/cm2 or more to decrease the fiber diameter to about 0.01 to 1 xcexcm, or by treating a suspension of a cellulose material in a media agitating mill several times. These apparatuses can be used singly or in combination of two or more to achieve the object of the present invention.
The drying of the mixture of a fine cellulose and a low-viscosity water-soluble dietary fiber can be conducted by a known method. However, in practicing the drying, an optimum method should be selected depending upon the water content in the mixture to be dried and the state of the mixture. In drying a slurry mixture, for example, there can be used spray drying, drum drying, alcohol precipitation, etc. In drying a muddy mixture or a rice cake-like mixture, there can be used tray drying, belt drying, fluidized bed drying, freeze-drying, microwave drying, etc. In order to obtain a composite which is improved in solubility and redispersibility in water, it is preferred to spray-dry a slurry mixture. In order to reduce the drying cost, alcohol precipitation, pressing, tray drying which is capable of drying a mixture of high solid content, and fluidized bed drying methods are preferred. The upper limit of water content in the dried mixture is preferably 15% by weight or less, particularly preferably 10% by weight or less, more preferably 6% by weight or less in view of the handleability (easiness of handling) and storage stability of the dried mixture.
The dried mixture obtained by drum drying, tray drying, belt drying or the like has a thin sheet shape or a lump shape. Therefore, it is preferable that the dried material is pulverized by an appropriate method such as impact type pulverizer, jet mill or the like and powderized to such a degree that almost all the powder can pass through a screen having an opening of 425 xcexcm.
The cellulose-containing composite of the present invention can be used in various foods. Examples of such foods are drinks such as favorite drinks (e.g. coffee, black tea, powdered tea, cocoa, adzuki-bean soup with rice cake and juice), milk-based drinks (e.g. raw milk, processed milk, lactobacillus drink and soy-milk), nutrient-fortified drinks (e.g. calcium-fortified drink), dietary fiber-containing drinks and the like; ice, such as ice cream, iced milk, soft cream, milk shake, sherbet and the like; milk products such as butter, cheese, yogurt, coffee whitener, whipping cream, custard cream, pudding and the like; processed oil and fat foods such as mayonnaise, margarine, spread, shortening and the like; condiments such as soups, stew, sauce, dripping, dressing and the like; gel- or paste-like foods such as spice pastes (e.g. mustard paste), jam, fillings (e.g. flour paste), bean jams, jelly and the like; cereal foods such as bread, noodle, pasta, pizza, premixes and the like; Japanese-style and western-style cakes such as candy, cookie, biscuit, hot cake, chocolate, rice cake and the like; marine paste products such as boiled fish paste, fish cake and the like; livestock products such as ham, sausage, hamburger and the like; side dishes taken with cooked rice or bread, such as cream croquette, bean jams for Chinese foods, gratin, dumpling stuffed with minced pork, and the like; delicacies such as salted fish guts, vegetables pickled with sake lees, and the like; liquid diets such as tube fed liquid diet, and the like; and pet foods, and the like.
In these applications, the cellulose-containing composite of the present invention acts as a suspension stabilizer, an emulsion stabilizer, a thickener and stabilizer, a foam stabilizer, a cloudiness agent, a texture-imparting agent, a fluidity improver, a shape-retaining agent, a water separation-preventing agent, a body-modifying agent, a powderizing agent, a dietary fiber agent, a low calorie agent for oil and fat replacement, etc. The effects of the present invention can be exhibited even when the above foods vary in shape or cooking method as seen in retort foods, powder foods, frozen foods and foods for electronic oven.
Since the present cellulose-containing composite gives a low viscosity and contains a fine cellulose of small particles, it is characterized in that the food produced with the composite is plain to the tongue, passes through the throat comfortably, is low in roughness to the tongue and, therefore, gives good feeling when taken into the mouth.
The present cellulose-containing composite is suitable particularly as a dietary fiber material for tube fed liquid diet. Currently, in the art of tube fed liquid diets, it is being attempted to use both a water-soluble dietary fiber and a water-insoluble dietary fiber. Some tube fed liquid diets of this kind are already being marketed but they do not have such sufficient properties as described below. A tube fed liquid diet is administered to human body through a tube and must flow down through the tube at a fairly low speed at a constant speed over a long period of time. In the above commercial products, however, there are cases that the water-insoluble component clogs the clamp of the tube (the clamp controls the speed of flowing down). Currently, the tubal liquid food is administered by opening the clamp as necessary to eliminate the clogging. The present cellulose-containing composite gives a low viscosity and the particles of the fine cellulose hardly give rise to flocculation. Therefore, when the present composite is used in a tube fed liquid diet, there occurs substantially no clogging at the clamp of the tube. Moreover, since the present composite contains a water-soluble dietary fiber and a water-insoluble dietary fiber, the present composite is highly excellent as a dietary fiber material for tube fed liquid diet.
When the cellulose-containing composite of the present invention is used in a food, the main materials of the food and, as necessary, a spice, a pH-controlling agent, a thickener and stabilizer, a salt, a saccharide, an oil or fat, a protein, an emulsifier, an acidulant, a food color, etc., they are subjected to mixing, kneading, stirring, emulsification, heating, etc. by using the same apparatus(es) as ordinarily used in the production of various foods.
The content of the present cellulose-containing composite in food varies depending upon the kind of food, etc. but is preferably about 0.01 to 15% by weight based on the total weight of the food. The content is preferably about 0.02 to 3% by weight when the present composite is intended to be used mainly as a stabilizer. The content is preferably about 0.5 to 15% by weight when the present composite is intended to be used mainly as a dietary fiber material (for tube fed liquid diet, etc.) or as a material for oil and fat replacement.
Next, the present invention is described in detail below by way of Examples.
The measurements were made as follows.
Average Particle Size and Proportion of Particles of 10 xcexcm or more in the composite
(1) Distilled water is added to 3.0 g (as solid content) of a sample to make the total amount 300 g.
(2) The mixture is dispersed at 15,000 rpm for 5 minutes using Ace Homogenizer AM-T (a product of NIPPON SEIKI CO., LTD.).
(3) The resulting dispersion is measured for particle size distribution using a laser diffraction type particle size distribution measuring apparatus (LA-910, a product of HORIBA SEISAKUSHO CO., Ltd.). xe2x80x9cAverage particle sizexe2x80x9d is the particle size of 50% cumulative volume, and xe2x80x9cproportion of particles having particle sizes of 10 xcexcm or morexe2x80x9d is the proportion (%) in volume distribution.
Viscosity of Composite
(1) Distilled water is added to 9.0 g (as solid content) of a sample to make the total amount 300 g.
(2) The mixture is dispersed at 15,000 rpm for 5 minutes using Ace Homogenizer AM-T (a product of NIPPON SEIKI CO., LTD.).
(3) The resulting dispersion is measured for viscosity, using a BL type viscometer (a product of Tokyo Keiki) at 60 rpm (rotor) at 25xc2x0 C. (dispersion temperature). The unit of viscosity is mpas.
Colloidal Content of Composite
(1) Distilled water is added to 0.75 g (as solid content) of a sample to make the total amount 300 (2) The mixture is dispersed at 15,000 rpm for 2 minutes using Ace Homogenizer AM-T (a product of NIPPON SEIKI CO., LTD.).
(3) 10 ml of the resulting dispersion is accurately taken in a weighing bottle and accurately weighed.
(4) 40 ml of the remaining dispersion is transferred into a centrifuge tube and is subjected to centrifugation at 2,000 rpm for 15 minutes using H-300 (a centrifuge produced by Kokusan Enshinki). 10 ml of the upper liquid is accurately taken in a weighing bottle and accurately weighed.
(5) The weighing bottles of (3) and (4) are heated in a dryer of 105xc2x0 C. for 10 hours to subject the contents to evaporation to dryness.
(6) The solid content of (3) is accurately weighed and taken as A g.
(7) The solid content of (4) is accurately weighed and taken as B g.
(8) A correction is made for water-soluble components (the proportion (S%) of the low-viscosity water-soluble dietary fibers and other water-soluble substances contained in composite of the total), and the colloidal content is calculated using the following formula.
Colloidal content (%)=[(Bxe2x88x92Axc3x97S/100)/(Ax(1xc3x97S/100))]xc3x97100